Question

A moving body of mass m and velocity v after colliding from a wall returns back (rebounds) with velocity v. The change in momentum will be
(A) 2 mv
(B) mv
(C) – mv
(D) zero

Answer 1

Answer:

it will be 2mv what i think

Explanation:

Considering that magnitude of velocity after rebound does not change amounts to elastic collision. For that momentum will have to be transferred to the wall which varies from a maximum of 2mv to zero depending upon whether the collision is head on ( a complete reversal of direction) or straight on (maintaining same direction). The question why the wall does not appear to move with a fraction and small velocity is important. Of course it is too heavy and its velocity is negligible. But in addition it gets scattered amongst particles in the wall and thus dissipates.

Answer 2

Answer:

Change in Momentum will be 2MV

Explanation:

In this question,

We have been given that,

A body of mass M and velocity V after colliding from a wall returns back with the velocity V

We need to find the Change in Momentum

Mass = M

Initial velocity = V

Final velocity = -V

 (Negative sign indicates the change in direction)

Final momentum = Mass × Final velocity

                            = -MV

Change in momentum = Final Momentum - Initial Momentum

= -MV - MV

= -2MV

Therefore, change in Momentum will be 2MV